I guess military tech always finds its way home. Pittsburgh city officials believe their police department’s use of a Long Range Acoustic Device (LRAD) at last week’s G20 protests was “the first time the sound cannon had been used publicly.”

Police used the device to emit a painful shrill that forced demonstrators to cover their ears and withdraw while police threw tear gas and stun grenades. “Other law enforcement agencies will be watching to see how it was used,” Pittsburgh’s police bureau chief told the NY Times. “It served its purpose well.”

Whether or not you think the protesters have a right to demonstrate or are anarchists without a permit to march, it’s still pretty eye-opening to see tech like that used at home.

As a non-lethal weapon, sound canons have been mounted to vehicles by the U.S Army, installed on American warships to warn incoming vessels, defended private cruise ships against Somali pirates, and were at the ready (though not used) at the 2004 Republican National Convention in New York.

But this is the first time LRAD has been used against U.S civilians. According to reports, 20 people were arrested, but there were no serious injuries. [New York Times]